Counter-wave pulse jet engine

ABSTRACT

A pulse jet engine having a housing forming a longitudinal, enclosed resonance chamber with spaced end walls functioning as reflecting walls and an exit port arranged substantially midway between the end walls. Ports are provided in the end walls for permitting a gas, such as air, to pass into the chamber. Flap valves are associated with these ports for closing same during intermittent combustions occurring in the chamber. The housing may include concentrically arranged inner and outer tubes, with adjacent ends of these tubes provided with the intake ports. The end of the outer tube spaced from its one end extends beyond the curves toward the adjacent end of the inner tube to form an annulus arranged for deflecting gases passing between the inner and outer tubes. This annulus has a concentric opening forming the exit port. A tailpipe may be connected concentrically to the annulus and arranged extending coaxially from the inner and outer tubes. Further, a reflecting wall having a port and an associated flap valve is arranged in the tailpipe for making the tailpipe a further resonance chamber.

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Tompkins Nov. 19, 1974 COUNTER-WAVE PULSE JET ENGINE Primary ExaminerC.J. i-i 1 1sa r g 7 Assistant Examiner-Warren Olsen [76] Inventor g p g gwacaster Attorney, Agent, or Firm-Clarence A. OBrien;

Jae Harvey B. Jacobson [22] Filed: Feb. 8, 1973 [21] Appl. No.: 330,64357 ABSTRACT A pulse jet engine having a housing forming a longitu- [52]U.S. Cl 60/248, 60/39.77, 60/39.8 dinal, enclosed resonance chamber withspaced end [51] Ilit. C]. F02k 7/04 walls functioning as reflectingwalls and an exit p [58] Field of Search 60,247 arranged substantiallymidway between the end walls. 39'78 Ports are provided in the end wallsfor permitting a gas, such as air, to pass into the chamber. Flap valves[56] References Cted are associated with these ports for closing sameduring U T STATES PATENTS intermittent combustions occurring in thechamber. 1,069,694 8/1913 Hayot 60/247 The housing may includeconcentrically arranged 2,471,832 5/1949 McCollum 60/248 inner and outertubes, with adjacent ends of these 2523379 50 Kol s 60/247 tubesprovided with the intake ports. The end of the Dunbar outer tube pacedfrom its one end extends beyond 27331646 3/l956 60/249 the curves towardthe adjacent end of the inner tube i to frgrn an antrlilulus arranggdfotr detflgctin g lgases palss- 3,185,871 5/1965 Bodine..... 60/39.76 Lewee" F 1S annu 3 486 331 12/1969 Brown 60/39.77 I a concemnc openmgformmg the A tall em r p1pe may be connected concentrically to theannulus FOREIGN PATENTS OR APPLICATIONS and arranged extending coaxiallyfrom the inner and 130,959 2/1951 Sweden.... 60/269 outer tubes.Further, a reflecting wall having a port 167,774 8/1950 Austria 60/269and an associated flap valve is arranged in the tailpipe for making thetailpipe a further resonance chamber.

10 Claims, 2 Drawing Figures COUNTER-WAVE PULSE JET ENGINE BACKGROUND OFTHE INVENTION 1. Field of the invention This invention relates generallyto a combustion engine, and particularly to a counter-wave pulse jetengine.

2. Description of the Prior Art The intermittent duct, or pulse jetengine has been long known, and was used to power the V-l buzzbombsdirected against London during World War II. Development of the pulsejet engine since that time, however, has been slight due to inherentnoise problems. Accordingly, attention has been directed to the thermalor turbo-jet and continuous duct or ram engines.

The loud noise in a conventional pulse jet engine is due to a pulsedwave passing out of the open, exhaust end of the combustion chamber,overshooting due to inertia after the driving pressure on the wave hasdissipated, coming to a stop, and being drawn back into the chamber bythe suction which was created by the wave initially passing out of thechamber. The wave will travel back toward the intake end of the chamberuntil the suction is balanced, and will again overshoot and cause apressure wave to start to build-up in the tube. As this pressure wavereaches the intake end of the tube, a combustible mixture, which wasdrawn into the tube when the suction wave reached the intake, is forcedinto the ever narrowing space between the intake port and the igniterplate. Heat from the last burning is stored in the adjacent igniterplate, and high pressure from the effect of ramming the wave into thenarrow space acts, once the engine is operating, together with thestored heat to ignite the mixture. Gases being forced out of the exhaustopening produce thrust which can be used in any suitable, known manneras motive power. The input suction wave, however, is 90 out of phasewith the exhaust wave that is, the suction is 90 away in space from theexhaust at the frequency of operation therefore, the sound from theengine is extremely loud.

A recent attempt to improve the operation of the pulse jet engine is setout, for example, in US. Pat. No. 3,486,331, wherein a reflecting wallis inserted in the conbustion chamber towards the exit end thereof forforming a closed-tube resonance chamber. The pressure waves formed bythe intermittent combustion in the combustion chamber will be reflectedoff this reflecting wall and off the wall formed by closed valves at theintake end of the chamber, which causes a more rapid build-up ofpressure and initial explosive force in the chamber. Ports provided inthe reflecting wall permit high pressure periods to force combustiongases down a tailpipe. Since, by proper design, a plane of substantiallyequal pressure will exist at the reflecting wall, a continuous flow ofair will pass through the ports provided in the reflecting wall and exitfrom the engine. In this manner, noise from the engine will be at acontinuous, reduced level. and operating efficiency of the engine willbe increased.

SUMMARY OF THE INVENTION It is an object of the present invention toprovide a pulse jet engine having an improved closed resonance chamberarrangement providing an even further reduced noise level and increasedefi'iciency as compared to known arrangements.

It is another object of the present invention to provide a pulse jetengine which uses some of the sound energy emitted by the engine to pumpadditional air. thereby lowering sound output, increasing engineefficiency by increasing the volume exhausted and allowing the exhaustport to be so restricted as to increase the pressure and speed of thegases exhausted, and providing internal engine cooling.

It is yet another object of the present invention to provide a pulse jetengine having one or more closed resonance chambers in which the totallength of these chambers is greatly increased without a substantialincrease in the overall size of a unit of, for example, a given thrust.

These and other objects are achieved according to the present inventionby providing a combustion engine, comprising: a housing forming anenclosed resonance chamber; a port provided in the housing forpermitting a fluid to pass into the chamber; valve means associated withthe port for closing same during intermittent combustion occurring inthe chamber; and means provided on the housing and arranged between theport and a reflecting wall of the chamber spaced from the port forpermitting combustion gases to exit the chamber. Advantageously, theexit port is arranged substantially midway between the inlet port andthe re- I flecting wall.

According to an advantageous feature of the present invention, thereflecting wall is also provided with an intake port and an associatedvalve means for admitting air into the resonance chamber when acondition of low pressure is present in a portion of the chamberadjacent the valve means.

The housing of a preferred embodiment of the present invention includesconcentrically arranged inner and outer tubes, with adjacent one ends ofthe tubes provided with the intake ports, and port provided blockingmembers arranged in the tubes at the one ends for blocking same.

The inner and outer tubes also have other ends spaced from the one ends.The other end of the outer tube extends beyond and curves toward theother end of the inner tube and forms an annulus arranged for deflectinggases passing between the inner and outer tubes. This annulus forms theexit port with an opening arranged concentrically with respect to thetubes.

A tailpipe may be connected to and arranged concentric with the annulus,and arranged extending coaxially from the inner and outer tubes. Afurther blocking member having a port may be arranged in the tailpipetogether with an associated valve element for making the tailpipe afurther resonance chamber.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view, partlycutaway and in section, showing a counter-wave pulse jet engineaccording to the present invention.

FIG. 2 is a vertical, longitudinal sectional view showing the engine ofFIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 of the drawingsshow a counter-wave pulse jet engine according to the present invention.This engine 10 has a housing 12 forming an enclosed resonance chamber14.

Chamber 14 is advantageously formed by constructing housing 12'. from apair of concentrically arranged inner and outer tubes 16 and 18. Theadjacent ends 20 and 22 of tubes 16, 18 are provided with blockingmembers 24 and 26 arranged for blocking the associated tube ends.

A plurality of ports 28 and 30 are provided in blocking members 24, 26and conventional flap valves 32 and 34 are associated with ports 28, 30,for closing same during intermittent combustions occurring in chamber14. During periods when a condition of low pressure is present in atleast a portion of the chamber adjacent the valves 32, 34, ports 28, 30admit air into the resonance chamber 14. Valve supports 35 and 36 arearranged for mounting flap valves 32, 34 in any known manner. An exitport 37 is provided on the housing, and is arranged between intake ports28 and 30 for permitting combustion gases to exit chamber 14. This exitport 37 is advantageously arranged substantially midway between ports 28and 30.

Tubes l6, 18 have ends 38 and 40 spaced from ends 20, 22. End 38 of tube16 extends beyond and curves toward end 40 of tube 18, and forms anannulus 42 arranged for deflecting gases passing between tubes 16, 18.Annulus 42 forms exit port 37 with an opening arranged concentricallywith respect to tubes 16, 18.

A tailpipe 44 terminating in a converging-diverging nozzle 45 may beconnected to and arranged concentric with annulus 42. This tailpipe 44extends coaxially from tubes 16, 18. A further blocking member 46 havinga plurality of ports 48 is arranged in tailpipe 44 together with aplurality of flap valves 50 associated with ports 48 for making tailpipe44 a further resonance chamber. Abutments forming a converging-divergingnozzle 51 may be provided to also serve as supports for flap valves 50.

Tube 16 is advantageously provided with a canopy portion 52 arrangedextending from end 38 of tube 18 and away from tubes 16, 18 for forminga chamber 54 having a volume larger than a fluid volume passed throughports 28, 30. This canopy portion 52 terminates in an opening 55allowing gases, such as air, to flow into chamber 54.

A conventional jet engine fuel 56, such as gasoline or kerosene, may befed from a conventional container 58 through a hose 60 into aconverging-diverging nozzle 62 extending from end 22 of tube 18.Blocking member 26 may be given a substantially bullet-shape to act as apressure increasing air-ram. A spark plug 64 is shown as arranged intube 18 for initially firing a mixture of air and gas passing into thecombustion chamber. Valve supports 35, 36 also function as igniterplates which heat upon the initial or first few combustions in engine 10such that subsequent combustions will be spontaneous and it will not benecessary to further actuate spark plug 64.

Other suitable elements, such as a glow plug, may be used in place ofspark plug 64. Heat radiating vanes or fins 66 may be arranged abouttube 18 to help pass heat from the hotest spots in tube 18 to the gasesin the counter-wave space, or resonance chamber portion, between tubesl6, 18. Further, conventional heat and sound insulation (not shown) maybe arranged in a known manner around the forward portion of engine 10.

An engine 10 according to the present invention operates by initiallyhaving air from an external source (not shown) blown through opening 55into nozzle 62. This air, and more to be drawn in by aspiration. passesthrough nozzle 62, where the pressure is low due to high velocity, andkerosene, gasoline, or other fuel 56 is passed from container 58 throughhose 60 and mixed with the air in the venturi formed by nozzle 62. Asthe mixture is expanded at the downstream side of nozzle 62, thevelocity head of the incoming air is converted to pressure, and themixture is forced through flap valves 28, 30.

A spark is applied at the inside end of spark plugs 64 by, for example,high voltage electricity from a conven tional source (not shown).Combustion will start when the mixture is right, it will reach explosionvelocity as the pressure rises, the valves 28, 30 will be closed, and asound wave will be started out of tube 18 toward its open end 40. Someof the gases being pushed out of tube 18 by this sound, or pressure waveare turned back or deflected by annulus 42 and become part of acounter-wave in the space between tubes 16 and 18. This counter-wavewill cause air to be drawn into the resonance chamber 14 through ports30, and valves 34. Not all of the combustion gases, however, aredeflected by annulus 42, the remainder flowing through exit port 37.This undeflected portion of gases passes into tailpipe 44, which isadvantageously the same length as the counter-wave space that is, thesame length as one half the length of resonance chamber 14 and,therefore, will return the wave in phase with the return from thecounter-wave. The counter-wave return will pass into tube 18, overshoot,and cause a mixture igniting, pressure buildup at the intake end of tube18. Additional aspiration is achieved by alternate suctions at valves 32and 34. The sound wave in tailpipe 44 bounces off that portion ofblocking member 24 which cooperates with flap valves 34 to reflectivelyblock end 20 of tube 16, but when the pressure in tailpipe 44 is higherthan in downstream smoothing chamber 68, some of the gases pass throughports 48 and valves 50 into smoothing chamber 68. Pressure is stored atnear peak sound pressure in smoothing chamber 68 until it can pass outthrough nozzle 45. It is this air passing out of nozzle 45 which causesa suction inside of chamber 14 and draws additional air into engine 10.Once engine 10 is started, the external air pressure source may be shutdown.

The foregoing is considered as illustrative only of the principles ofthe invention. Further, since numerous modifications and changes willreadily occur to thsoe skilled in the art, it is not desired to limitthe invention to the exact construction and operation shown anddescribed, and accordingly all suitable modifications and equivalentsmay be resorted to, falling within the scope of the invention.

What is claimed as new is as follows:

1. A combustion engine, comprising, in combination:

a. a housing forming an enclosed, resonance chamber having a pair ofadjacent end portions;

b. a port provided in one of the housing end portions for permitting afluid to pass into the chamber;

c. valve means associated with the port for closing same duringintermittent combustions occurring in the chamber;

d. a further port arranged at the other of the housing end portions andbeing also provided with an associated further valve means for admittingair into the resonance chamber when a condition of low pressure ispresent in a portion of the chamber adjacent the further valve means;

e. deflection means provided on the housing and arranged between thechamber end portions for deflecting fluid passing between the chamberend portions; and

f. exit means provided on the housing and arranged between the chamberend portions for permitting combustion gases to exit the chamber.

2. A structure as defined in claim 1, wherein the exit permitting meansis arranged substantially midway between the chamber end portions.

3. A combustion engine, comprising, in combination:

a. a housing forming an enclosed, resonance chamber;

b. an intake port provided in the housing for permitting a fluid to passinto the chamber;

c. valve means associated with the intake port for closing same duringintermittent combustions occurring in the chamber;

d. an exit port provided in the housing for permitting a fluid to passfrom the chamber;

e. valve means associated with the exit port for permitting apredetermined pressure to open the associated valve means and pass afluid from the chamber;

f. a tailpipe connected to and surrounding the exit port, and arrangedextending from the housing; and

g. a blocking member having a further port and arranged in the tailpipe,and a valve element associated with the further port for making thetailpipe a further resonance chamber.

4. A structure as defined in claim 3, wherein the housing includesconcentrically arranged inner and outer tubes, with adjacent one ends ofthe tubes provided with ports, and means having the ports arranged inthe tubes at the one ends for blocking same.

5. A structure as defined in claim 4, wherein the tubes have other endsspaced from the one ends, and the other end of the outer tube extendsbeyond and curves toward the other end of the inner tube and forms anannulus arranged for deflecting gases passing between the inner andouter tubes, the annulus forming the exit permitting means as an openingarranged concentrically with respect to the tubes.

6. A structure as defined in claim 1, wherein the housing includesconcentrically arranged inner and outer tubes, with adjacent one ends ofthe tubes provided with the ports, and means having the ports arrangedin the tubes at the one ends for blocking same.

7. A structure as defined in claim 6, wherein the tubes have other endsspaced from the one ends, and the other end of the outer tube extendsbeyond and curves toward the other end of the inner tube and forms anannulus arranged for deflecting gases passing between the inner andouter tubes, the annulus forming the exit permitting means as an openingarranged concentrically with respect to the tubes.

8. A structure as defined in claim 7, wherein the outer tube is providedwith a canopy portion arranged extending from the one end of the outertube and away from the tubes for forming a chamber having volume largerthan a fluid volume passed through the blocking means ports in an enginecycle.

9. A structure as defined in claim 7, further including a tailpipeconnected to a concentric with the annulus,

and arranged extending coaxially from the inner and outer tubes.

10. A structure as defined in claim 9, further including a blockingmember having a port and arranged in the tailpipe, and a valve elementassociated with the port for making the tailpipe a further resonancechamber.

1. A combustion engine, comprising, in combination: a. a housing formingan enclosed, resonance chamber having a pair of adjacent end portions;b. a port provided in one of the housing end portions for permitting afluid to pass into the chamber; c. valve means associated with the portfor closing same during intermittent combustions occurring in thechamber; d. a further port arranged at the other of the housing endportions and being also provided with an associated further valve meansfor admitting air into the resonance chamber when a condition of lowpressure is present in a portion of the chamber adjacent the furthervalve means; e. deflection means provided on the housing and arrangedbetween the chamber end portions for deflecting fluid passing betweenthe chamber end portions; and f. exit means provided on the housing andarranged between the chamber end portions for permitting combustiongases to exit the chamber.
 2. A structure as defined in claim 1, whereinthe exit permitting means is arranged substantially midway between thechamber end portions.
 3. A combustion engine, comprising, incombination: a. a housing forming an enclosed, resonAnce chamber; b. anintake port provided in the housing for permitting a fluid to pass intothe chamber; c. valve means associated with the intake port for closingsame during intermittent combustions occurring in the chamber; d. anexit port provided in the housing for permitting a fluid to pass fromthe chamber; e. valve means associated with the exit port for permittinga predetermined pressure to open the associated valve means and pass afluid from the chamber; f. a tailpipe connected to and surrounding theexit port, and arranged extending from the housing; and g. a blockingmember having a further port and arranged in the tailpipe, and a valveelement associated with the further port for making the tailpipe afurther resonance chamber.
 4. A structure as defined in claim 3, whereinthe housing includes concentrically arranged inner and outer tubes, withadjacent one ends of the tubes provided with ports, and means having theports arranged in the tubes at the one ends for blocking same.
 5. Astructure as defined in claim 4, wherein the tubes have other endsspaced from the one ends, and the other end of the outer tube extendsbeyond and curves toward the other end of the inner tube and forms anannulus arranged for deflecting gases passing between the inner andouter tubes, the annulus forming the exit permitting means as an openingarranged concentrically with respect to the tubes.
 6. A structure asdefined in claim 1, wherein the housing includes concentrically arrangedinner and outer tubes, with adjacent one ends of the tubes provided withthe ports, and means having the ports arranged in the tubes at the oneends for blocking same.
 7. A structure as defined in claim 6, whereinthe tubes have other ends spaced from the one ends, and the other end ofthe outer tube extends beyond and curves toward the other end of theinner tube and forms an annulus arranged for deflecting gases passingbetween the inner and outer tubes, the annulus forming the exitpermitting means as an opening arranged concentrically with respect tothe tubes.
 8. A structure as defined in claim 7, wherein the outer tubeis provided with a canopy portion arranged extending from the one end ofthe outer tube and away from the tubes for forming a chamber havingvolume larger than a fluid volume passed through the blocking meansports in an engine cycle.
 9. A structure as defined in claim 7, furtherincluding a tailpipe connected to a concentric with the annulus, andarranged extending coaxially from the inner and outer tubes.
 10. Astructure as defined in claim 9, further including a blocking memberhaving a port and arranged in the tailpipe, and a valve elementassociated with the port for making the tailpipe a further resonancechamber.